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MG MGA - oil and water don't mix - gasket problems

Got my car back from the mechanic today. Everything was good to go. They were finishing up by changing the oil and the oil looked like Bailey's Irish Cream. The mechanic said it had to be the head gasket because water from the radiator was leaking into the oil. When they pressurized the radiator, more mocha-like fluid came out of the oil pan.

I took it home and decided to mess with it here. How hard is it to replace a head gasket, especially since some of the bolts look rusty? Is there anything else that could be causing this? I guess what I'm getting at is does this mean that it's likely something else is screwed up? I don't want to start fixing stuff only to find out that I need a new engine.

I have a crossflow head on a 1622cc engine that's been bored out to 60 over. Do I use a standard 1622cc head gasket?

Thanks,

Darian
Darian Henderson

An overbore of 0.060" on a 1622 engine sounds like a lot. The block castings used by MG could have a lot of variation in cylinder wall thickness. If the water is getting in through a crack in the cylinder wall you are looking at another block or sleeving the cylinders.
On the other hand, you say that you have a crossflow head. Is it alloy? You could have a distorted alloy head that needs resurfacing.

Mick
Mick Anderson

Thanks for responding.

The .060" was done back in the 1970's, and it ran for a while like that. That's not to say that it hasn't cracked in the meantime, since it sat for over 20 years.

Is sleeving something that can be done at home?

The head is alloy (HRG). It worked fine when the car was parked 20+ years ago.

Some good news is that I got all the nuts loose and I didn't have to even work hard at it. I spayed the studs with oil and I'll try to remove the head tomorrow.

I've been thinking about getting an 1800 engine. My current engine has a lot of performance parts. Would, for example, the cam, valve springs, flywheel and cylinder head all fit on an MGB engine?

Thanks again,

Darian
Darian Henderson

Hi Darian. Sleeving the engine requires specialized machine shop equipment and cant be done at home. You can pull the head off and install a new head gasket at home. Be sure to remove and re install the head nuts in the proper sequence and be ure to tighten the nuts to the proper torque values. Use of a factory manual is recommended. Cheers, Glenn
Glenn

Darian- Thanks to Bill Spohn,he has the HRG fitting instructions.They use a lower torque than the original cast iron head.Maybe he will see this or try to get a hold of him here-http://wwcitymax.com/HRG.htmlw.rhodo.
He can,I'm sure recommend what gasket to use also
gary starr

If the head is still on, you might want to try a pressure test by putting air into each cyliner to see where it might leak out of. You listen to the exhaust pipe, the carb, or the valve cover to hear where the air is going. My concern is if it is a cracked walled and not a head gasket. I would bet it is the gasket. The 1800v is a great engine and a 5 main.
JEFF BECKER

I could not access the link given by Gary.
If Bill Spohn does not reply to this BBS thread I can give you a copy of his HRG instructions. I am sure that he would approve, as long as due credit is given.
You must use the special large, thick washers and a maximum tension of 40 ft/lb for the HRG cylinder head nuts.

Mick
Mick Anderson

060 oversize is the max available for a standard piston set for the MGA. I wouldn't worry about it.

It does sound as if at least the head gasket has gone. When you take the head off you need to have a look at the cylinder bores and see what state they are in. If they are smooth and free from scores, the head gasket will probably be the culprit. If they are rusty/ scored or pitted, you will need to take the engine out and have it overhauled.

Do make sure that you follow the correct order for undoing the nuts on the head as you remove it, otherwise you run the risk of damaging it. The correct sequence is in any workshop manual.
dominic clancy

If you presurize the cylinders for a leak down test, remove the radiator cap and fill radiator with water first.

Bubbling in the radiator is usually a blown head gasket, occasionally a cracked iron cylinder head if it was overheated (probably not cracked aluminum head). Cracked cylinder wall is very rare, only if it was excessively overbored, .080" o/s or larger, or if a broken piston damaged the cylinder wall.

With pressure applied, hissing at the tail pipe is a leaky exhaust valve. Hissing at the carburetor is a leaky intake valve. Hissing at the oil filler port is leaky piston rings blowing through the crankcase. All piston rings leak a little bit due to the ring end gaps. If compression readings are good a tiny hiss past rings is (usually) not serious. However, if an oil wiper ring is bad you can have high oil consumption even with good compression.

If the head gasket was leaking, remove head and remove all head studs. Touch a countersink tool at each of the head stud holes to remove any raised threads at top of block. Rub down top of block and bottom of head using a long whet stone with light oil and oval motion until you get a uniform buff finish indicating full surface contact. Check flatness with a long straight edge. If head is warped, have it resurfaced. The iron blocks are usually flat. Exception could be if it ran a long time with a compresison blow out in head gasket (usually between #2 & #3 cylinders). In that case the hot combustion gases blowing between cylinders might burn the top of the block or the cylinder head.
Barney Gaylord

Lets try again-http://www.rhodo.citymax.com/HRG.html
Thanks once again to Bill
gary starr

Thanks everyone. The shop did what Barney suggested, so it's probably the head gasket since steam was coming out of the radiator after it'd been running for 2 minutes.

The bolts are loose. Anyone have any ideas about how to remove the cylinder head? It's not budging.
Darian Henderson

The typical trick is to feed some rope into the bore through the spark plug hole, then turn over the engine to get the piston to compress the rope and break the head free. Should not need very much, and I use a wrench on the dog nut rather than the starter. Before trying the rope, reinsert the spark plugs and try it on the starter - the compressioin may be enough to break it free.

You have removed the rocker valve assembly haven't you!
dominic clancy

I wouldn't use the starter with the old rope trick either. Put it in gear and rock the car. A few taps on the side of the head (cushioned with a piece of wood) might help too. Do NOT be tempted to try an pry it off. That's a valuable head you've got there. I would definitely get confirmation on any special installation instructions for the HRG.
Derek Nicholson

Hi Darian. to remove the head, you can pull the spark plugs, and fill the cylinders with motor oil. Then put the car in gear, and push the car down the driveway. Hydraulic pressure will lift the head off the engine. This is a somewhat messy proposition, but works very well to remove stubborn cylinder heads without damage. Cheers, Glenn PS Just a reminder, that since there is coolant in your motor oil, you will needt to drain all the old oil, replace the oil filter, and then refill with fresh oil
Glenn

Thanks Derek and Dominic, the rope thing worked like a charm. I put it into 4th and pushed it forward and then I heard a small pop and it came out.

The head gasket didn't look to bad, but it looks like the cylinder head is busted.

Here's the head gasket:

http://img111.imageshack.us/img111/6287/gasket1wc4.jpg
http://img264.imageshack.us/img264/108/gasket2nx1.jpg

Here's the engine and the head:

http://img230.imageshack.us/img230/1471/headandengineep5.jpg

I've circled in blue the part that looks damaged. I thought for a moment that it was my handywork, but it looks old. It is also next to the only cylinder that had rust in it. (The sides of the cylinders seem pretty clean, though.)

http://img465.imageshack.us/img465/6668/holeinheadok5.jpg

Thanks to everyone who responded. Any thoughts would be appreciated.
Darian Henderson

PS I wasn't able to get this cable off very easily so I stopped messing with it. What is it for?

http://img260.imageshack.us/img260/4838/headandengine2zu6.jpg

Darian Henderson

It's the water temperature sensor and pipe. I'm sure Dominic has another rope trick for getting it unscrewed!

Steve
Steve Gyles

Try and avoid damage to that temperature sensor tube. It is a fluid filled tube and expensive to fix if broken.
That HRG cylinder head should be repaired, they are rare and very valuable items.

Mick
Mick Anderson

Darian- Don't give up yet,you have something worth saving.Here's what I had to do to mine-
http://i94.photobucket.com/albums/l119/garys_01/Dcp_0739.jpg
Here's a picture of my combustion chamber side-http://i94.photobucket.com/albums/l119/garys_01/Dcp_0741.jpg
Where yours is bad mine has a steel plug as you can see and the other one has a steel plug with a hole in it to let the coolant thru.
While you are working on it could you look on the flat pad next to the thermostat like here- http://i94.photobucket.com/albums/l119/garys_01/Dcp_0740.jpg
and let us know what the numbers are?
Any GOOD cylinder head shop will have no trouble repairing yours,the trick being finding one.Check with John Twist http://www.universitymotorsltd.com/ I did my A's first engine rebuild and the local shop didn't know how to work on MG's.Took it to John and he took it to his machinist who knew MGs. Good luck with your rebuild, Gary
gary starr

Darian, The alloy head can be welded and remachined quite successfully. Look for a specialist in your area. If you can't find someone or don't want to go down that path, I will buy it!! Steve is correct about the water sensor. It can be removed by carefully applying pressure through the thermostat opening (after the thermostat has been removed). Before you re-install the sensor, screw a brass sleeve into the head. I will email a photo of this brass piece to you and anyone who asks. I have fitted them to all my resto's. Brass on brass will never sieze and will separate easily next time you remove the head. It is a standard waterpipe fitting and widely available (at least in Aus.)
Barry.
BM Gannon

Well, it's good to know that it can be repaired. I was pretty disappointed to see the chip.

I've heard several people talk about how valuable this cylinder head is. How much are we talking, because I'm beginning to think that now is the time to drop in that MGB engine I've been wanting. The goal is that one day I would supercharge it, which you can't do with this head.

But seriously, depending one how much it's worth, I might sell it.
Darian Henderson

Hi Gary,

The number is 298/660. Just curious, but why do you ask?

http://img341.imageshack.us/img341/7346/headnumbermx1.jpg

Darian
Darian Henderson

Hello Darian,Bill Spohn is keeping a list of serial numbers.From what I understand from his work your head was the 298th one built in June of 1960.My head is A570/361,no one has been able to find out what the prefix "A" means.With out that prefix,#570 would have been made in 1963,instead of March 1961.Only one other "A" prefex head has been found.I understand your thoughts on supercharging,but HRG's you won't see everday.I have no idea what they are worth today,I got mine complete with 1 3/4 SU's and I know what I paid for it was way less than what I'd have to spend today to replace just the SU's. Thanks for your time Darian,Gary
gary starr

Hi, Darian. Mick, thanks for bringing this thread to my attention - too many things to do and too few hours to do them, and I'd overlooked it so far.

Gary is right, Darien, by keeping a list of heads I am trying to discern how the numbering went. I have contacted Derringtons and they say the records were destroyed years ago.

Our best guess is that yours was indeed the 298th head built, in June 1960.

Gary, I have 5 A prefix heads including yours and all appear to be 60s when they changed their numbering system a bit.

Darien, these heads are well worth saving. Yours appears to have suffered from old or no antifreeze with corrosive results, but a good shop can weld a ring into it where the erosion took place and resurface it. I have found that any shop that does motorcycle specialty work is adept in fancy alloy welding and machining (and probably does a good job, as come-backs from the local biker club can, I understand, be unpleasant...;-)

Take a look at the page I have (referenced above), which includes scans of original documentation and if you need any advice on it feel free to ask.

I was thinking of replicating a small poster sent from the factory if anyone is interested in a period piece.

BTW, the original HRG heads are allowed to run in some vintage race organisations while modern replicas are not, so if you ever decide to part with it, that would be the place to look. I'd advise you to keep it and use it though.
Bill Spohn

The trick with the temp sender is patience and penetrating oil, and a spanner that is EXACTLY the right size to avoid destroying the nut.
dominic clancy

It is my understanding from literature from Brodix and the like, that any extensive welding should be followed by heat treatment, as the heat affected area is now , soft, and weak. Shops that do top level race car head work should be good for this, as many use, and repair, aluminum heads.
Note that areas that were leaking show up as dark stains on the block, head, and gasket. Bill's remarks re antifreeze are dead on, and the problem is aggravated by gas leaks into the coolant, which acidify it. Correct retorque is critical.
Darian - As a newcomer to this, I suggest that you keep the car reasonably in the state it has been for all its life. It will be on the road sooner, it will go quite well, and preserve a bit of the past, and you'll probably be just as happy as with the 1800. If you later decide to go really fast, then use a modified 1800, and it will have to be modified to outrun the 1622 crossflow.
FRM
FR Millmore

Good to hear from the expert,Bill.What are the years of those heads with the A prefix?
Another place to have head work done would be a shop who does aircooled VW work,most likely to be in California and found in a magazine like Hot VW's.Also a good source of head washers,you need the larger stud ones,pre '71 I think
gary starr

Thanks everyone. Now I have an idea what to do. I emailed John Twist from his website. Hopefully he'll get back to me.

Got the temp sensor bolt loose.
Darian Henderson

By the way, is there any chance that this was caused by a fault in the engine block?

Thanks
Darian Henderson

Little to zero. See my post above. The large areas of black staining from leakage are due to loose nuts, the corroded area is from bad antifreeze and erosion once it started to leak.
FRM
FR Millmore

Well that's good to know. I guess it's off to the machine shop. I just didn't want to fix it only to find out that it broke again because of the engine block.
Darian Henderson

PS A stupid question, but loose nuts where?
Darian Henderson

Probably the nuts that hold the cylinder head down.

The washers underneath the cylinder head nuts are special hardened ones, and when people lose them and use normal ones, they flatten under the load. The head is then effectively looser than it should be - with the consequences you see here when an aluminium head is involved.

dominic clancy

Thanks Dominic. I'm quite sure that normal ones were used, as they were bent when I removed them. I realize you're in Switzerland and not TX, but do I just go and as for "hardened washers" at a auto parts store?
Darian Henderson

Yep, cylinder head stud nuts. And normal settling also makes the gasket loose, especially after 20 yrs.
You may have to get washers from a machine shop supply place like MSC, #74213505 $0.29ea or 82429044 $0.69 "Finished flat washer, case hardened, 13/32 ID, 7/8OD, .125 thick." You might get them from a real autoparts store, if you can find one of those with greybeards, otherwise they wanna know "wha' zit fer" and you are screwed. Be careful buying from other sources as some otherwise good washers are too big on the ID and not flat, and let the nut sit cattywhompus, screwing things up. The "heavy duty washer" supplied lately by Moss as OE HD should be the right item, but is crap, soft as mush. The nuts sold by Moss are OK, longer than the
OE; in fact they appear to be SAE "high nuts", again in theory from a good parts store.
FRM
FR Millmore

Thanks a lot, FRM, that was just what I was looking for.

Does anyone think it's possible that the fact that the bolts were loose caused water to leak, which in turn eroded the head?
Darian Henderson

See above "Little to zero..."
Check yr email!
FRM
FR Millmore

This thread was discussed between 17/03/2007 and 20/03/2007

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